1. Field of the Invention
This invention relates to a recording apparatus for recording information on a recording medium by the use of a beam, and more particularly to a recording apparatus in which the scanning velocity of the beam scanning over the recording medium is controlled.
2. Description of the Prior Art
In the prior art recording apparatus for recording information by projecting a light beam on a recording medium, a rotatable polygon mirror rotatable in one direction or a mirror vibrating within a predetermined angle has been often used as the deflector for deflecting the light beam.
In such a recording apparatus, a velocity detector has been provided within the motor for driving the rotatable polygon mirror or the reciprocally rotatable motor for driving the mirror to render the deflection velocity of the light beam constant, and the driving of the deflector has been controlled by the output of the velocity detector.
However, to enhance the control accuracy in such a velocity control, it has been necessary to increase the number of the velocity detectors to be contained within the motor, to enhance the accuracy with which these velocity detectors are arranged, or to reduce the irregularity of the sensitivity of the detector and this has involved technical difficulties and has become expensive.